Expanding piston



March 18, 1930. 5 w GALLOWAY 1,759,928

EXPANDING PISTON Filed April 25, 1929 i 1' 1 A6 7 r 1 &

Inventor 5. .6 W aZiazway Patented Mar. 18, 1930 UNITED STATES PATENEXPANDING PISTON Application filed April 25,

This invention relates to pistons and more especially to expandingpistons adapted for use in internal combustion engines.

The primary object of this invention is to provide an improved expandingpiston of this type which may be capable of adjust-' ment as to tension,the piston being cast in two parts, each art forming a spiral curvefitted together with overlapping flanges.

The springs creating the tension being fitted inside the pistons, areadjustably associated with the coupling or wrist pin of the piston.

A further object of the invention is to pro- 1 vide a piston of the typeabove set forth which will be comparatively simple in construction,readily and easily assembled or disassembled, and which will readilyadjust itself to take up all wear and whereby an even tension on 29 thewalls of the cylinder may be maintained at all times.

Another very important object of this invention is to provide anadjustable tension piston wherein the piston head is cast in two parts,one overla ping the other, to add strength and dura ility and to preventleak- Figure 3 is a vertical sectional view of the piston at rightangles to the point of view 5 shown in Figure 2.

Referring to the drawings in detail, it will be seen that the hereinillustrated embodiment of my invention comprises a piston formed intotwo complemental sections 5 and 6. Each of the piston sections 5 and 6com- 1929. Serial No. 357,994.

prises the head portions 7 and 8 respectively and the complemental skirtsections 9 and 10 respectively. It is to be noted that the head portionsof each of the sections is provided with the usual groove to receive theusual iston rings and that the downwardly extending skirt sections areeach formed to provide the usual bearings 12 and 13 respectively.

As illustrated the abutting edges of the 1 head and skirt portions ofeach of the complemental sections is irregular in outline, and it willbe seen that the curve or split of the piston starts at the top of thepiston in line with the center of the wrist pin bearing 12 on thesection 6 and circles around to the bottom of the piston in the sameposition on the other side. In so forming the piston, each casting thenforms a complete half circle so that the top 14 of the section 6, whichis circular in plan view is disposed in overlapping relation withrespect to the top 15 of the section 5, which top 15 is likewisecircular in plan and the peripheral edge of which, at one point of theperiphery is a apted to abut the inner face of the edge portion 8 of thecomplemental section 6.

It is also to be noted that bearings 12and 13 formed on intermediateortions ofthe skirt of the respective section, extend inwardly of thepiston to receive the opposite ends of a coupling or Wrist pin 16. Thesprings creating the tension are fitted inside the piston, each spring17 and 18 respectively, being coiled about the bearings 12 and 13respectively, the outer end of which springs are adapted to impingeagainst the keys 18 and 19 respectively, which keys are fixed insuitable manner to the wrist in 16 at the opposite ends of the pin and aj acent the respective bearings.

It is apparent that the springs can be adjusted so as to tension witheither set screws or split washers and that by means of tho tenslon, thepiston adjusts itself to the wear on the cylinder walls.

From the foregoing then, it will be seen that I have provided a simple,yet durable and eflicient expansible piston, capable of use in internalcombustion engines, and analogous uses, so constructed as to easily takecare of the natural wear, allowin the piston to adjustitself to thewalls of t e cylinder by means of the tension on the s rings inside thepistons as hereinbefore described. 5 While I have herein shown anddescribed certain detail structural features of my in vention, it is tobe understood that certain changes may be made therein, withoutdeparting from the spirit of the invention as described or the scope ofthe appended claims.

What is claimed is: 1. A piston composed of a pair of complei mentalsections, each of said sections comprising a head portion and a skirtportion having their ad acent edges disposed in abutting relation, saidadjacent edges being irregular in outline, a bearing formed on each ofsaid skirt sections and adapted for alignment with 7 each other, a wristpin extending through the aligned bearings, a coiled spring oneach ofsaid bearings and keyed on the wrist pin against which one end of eachspring is adapted to impinge.

2. A piston comprising a head portion, and

a downwardly extending skirt portion, diametrically opposed wrist pinbearings formed on the skirt portion and said piston being split todivide the piston into a pair of complemental sections, and said splitdefining a spiral curve starting at the top of the piston in line withthe center of one of the wrist pin bearings, and circling around to thebottom of the piston in the same position on the other side of thepiston, a wrist pin having its opposite ends received in the bearings, acoil spring on each of said bearings, and keys on the wrist pin againstwhich one end of each spring is adapted to impinge for yieldinglyexpanding the two sections.

3. A piston composed of a pair of complemental sections, each of saidsections comprising a head portion and a skirt portion having theiradjacent edges disposed in abutting relation, said adjacent edges beingirregular in outline, the head portion of each of said sections havingextensions formed thereon adapted to overlie each other to form I a topfor the piston, a bearing formed on the skirt portions of each of saidsections, a wrist pin extending through the bearings, and a coil springdisposed about said bearing and adapted for engagement with the wristpin as and for the purpose specified.

In testimony whereof I afiix my signature.

GEORGE W. GALLOWAY.

